Sound recording



June 17,1930.

w. c. JONES SOUND RECORDING Filed Jun 9, 1928 F/GI 2 /NVENTOP Wap/PEN r62 .Jo/v5.5

ArraP/vsy objectionable stidness Patented .newl 17 1930- UNITED STA TEsPAT-ENT oFFlcE i WARREN o. JONES,

omronrns, r-NcORPOM'rEp,

or'rLusnINe, Naw Yoan, AssIeNoB. rro BELL TELEPHONE LAB- or NEW Yoan, N. Y., A conronArIoN -or Nnw Yom:

sorrND .nEconmNe Application mea :une 9 It is the ob] ect of this invention to provide 5 -a 's1mple,` compact damping device of such a nature as to impart to the recorder a .substantially uniform response characteristic over -a wide range of frequencies.

. In accordance therefore with the general features of this invention the recorder is provided with an oil-filled damping unit havingA a wing-like member adapted to oscillate between two adjustable plates in accordance with the movementsV of therecorder armature. 'The damping may be regulated by varying the spacing of .the plates and the oil is confined without the introduction of any diaphragm attached to the wing member and clamped at its periphery to the unit casing.

In the drawing Fig. 1 is a -general view of one type of electrical recording device ping unit comprising this invention may be attached to damp the movements of the recording stylus. and 3 are sectional views of the damping unit which clearly indicate the construction employed. I Y

Referring now to Fig. 1, the' recorder 1 is of the balanced armature type and with respect-to the arrangement ofthe parts for translating electrical variations in the windingsv 24, 25 into mechanical vib'ratidns'of th'e-l recording stylus 2 is essentially the same as that disclosed in Patent 1,663,884 to Harri" son. The recording stylus is carried by a` stylus holder 3, the horizontal section` of which serves also as a supportinginember for the armature 4. When Aa record 5 is e- ,40

ing cut an oscillatory motionis imparted to the armature by the interaction of the currents corresponding to thesounds to be recorded and the magnetic ield of the recorder as fully described ,in the Harrison patent so that the stylus holder 3 will vibrate about its horizontal axis. Y

In order to' obtain a reasonably uniform response `over the desired frequency range it is usually necessary toiproviide such-vibratory systems with some sort of terminating im'- Y by means of a thin skin Figs. 2

192s. serial No. 284,244.

pedance for absorbing the energy not transmltted to the recording surface. Various methods accomplishing--this result have been proposed but the device shown in Figs. 2 and 3 has proven very satisfactory particularly for high quality work in which it is necessary to' maintain a uniform response throughout a wide range including the lower sound frequencies. In this device a winglike mamber 6.V which is preferably of duralumin or other llght, strong material, has a hollow cylindrical portion attachment to the stylus holder ofthe recorder indicatedin Fig. 1.f The face plates 9 and 10 are slotted and threaded for conveni ience in adjusting the size of the damping chamber 11 inthe casing 12. This chamber is 7 which i'sthreaded for easy i filled with a heavy viscous material which impedes the motion o'f the wing member. 6 as Ait vibratqs about its axis 13 and 14 according to the movements of the stylus holder. 'A

very'thin iieXible diaphragm 15 for confining the viscous material is held between rings 16 and 17 and clamped in place and protected from injury by the plug 18. A material suitable for this diaphragm is known as fish skin.

A central opening in the diaphragm is proy vided to permit the wing member 6 to be attached to the recorder and a locknut 8 holds this member in proper alignment and prevents the escape of the viscous liquid at this point. Care should be taken in clamping the diaphragm in place to see that it is not stressed radially for in such a case the resulting stiffness would materially alterpthe char-- 'acteristic of the recorder.'

7 Wh t is claimed is:

' 1. a vibration damping device, a casing, pair of spaced plates, a member .adapted the plates and viscous a to oscillate between tions of said member.'

h2. In a vibration damping` device, a casi-ng having a air of closely spaced` surfaces, aA member a' apted for rotary oscillatory vibration between the surfaces and viscous matter ibn the casing to resist the motion of said memer. l 3'. In a vibration damping device, a casing having a pair of adjustablyfspaced plates, a

wing-like member'betweenthe plates, viscous matter in the casing for im edng'the motion of said:member,"and a. thin exbl d iaphra m Asattached to saidmember and'f'saidfcasing or confining the viscous "matter,

In Witness whereof,y I hereunto subscI-fibe WARREN C. JQNE'S.-4r

' A. myfpame this 8th day of June, 1928. 

